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Chapter 03 Experimental Basis for Quantum Theory Version 110920, 110921 General Bibliography 1) Various wikipedia, as specified 2) Thornton-Rex, Modern Physics for Scientists & Eng, as indicated Outline • • • • • • • • • 3.1 X-rays and Electrons 3.2 Electron Charge 3.3 Line Spectra 3.4 Quantization 3.5 Blackbody Radiation 3.6 Photoelectric Effect 3.7 X-Ray Production 3.8 Compton Effect 3.9 Pair Production & Annihilation 3.1 X-rays and Electrons http://physics.kenyon.edu/EarlyApparatus/Static_Electricity/Geissler_Tubes/Geissler_Tubes.html http://www.oneillselectronicmuseum.com/page9.html http://www.beer-neon-signs.com/category/neon-business-signs Geissler tubes ~1857 3.1 X-rays and Electrons Discovered cathode rays could be shifted by a magnet http://www.magnet.fsu.edu/education/tutorials/museum/crookes_tube.html Cathode rays (now called electrons) Crookes Tubes ~1869 X-rays and Electrons Hand mit Ringen (Hand with Rings): print of Wilhelm Röntgen's first "medical" X-ray, of his wife's hand, taken on 22 December 1895 and presented to Ludwig Zehnder of the Physik Institut, University of Freiburg, on 1 January 1896[17][18] X-rays and Electrons 1896 plaque published in "Nouvelle Iconographie de Salpetriere", a medical journal. In the left a hand deformity, in the right same hand seen using radiography. The authors designated the technique as Röntgen photography. X-rays and Electrons JJ Thomson http://www.scifun.ed.ac.uk/pages/pp4ss/pp4ss-eoverm.html http://ixnovi.people.wm.edu/Onebeautifulexperiment2008/emexperimentbywilliamsendor3.html Charge of the Electron 3.3 Line Spectra http://nothingnerdy.wikispaces.com/DIFFRACTION+GRATING Pink Floyd: Dark Side of the Moon http://intro.chem.okstate.edu/1314f00/Lecture/Chapter7/Lec11300.html k2 364.56 2 k 4 nm k = 3,4,5,6 http://www.chem1.com/acad/webtext/atoms/atpt-3.html k2 364.56 2 k 4 nm 4 1 1 2 364.56 4 k 1 1 1 RH 2 2 n k 1 RH = 1.097e+7 m1 100 nm vis 10000 nm 1000 nm 3.3 Line Spectra 3.5 Blackbody Radiation http://www.mytightride.com/fof1fefl.html 3.5 Blackbody Radiation http://en.wikibooks.org/wiki/Wikijunior:How_Things_Work/Light_Bulb http://www.freefoto.com/preview/11-12-52/Electric-Light-Bulb http://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html 3.5 Blackbody Radiation Wein’s Law maximum 2.898 103 m K T Stefan-Boltzmann Law Total Intensity eT 4 5.6705 10 8 Watts m2 K 4 e = 1 for perfect blackbody 3.5 Blackbody Radiation Intensity UV IR 2 c kT 4 3.5 Blackbody Radiation Max Planck assumed some sort of oscillators filled the cavity AND energy difference between standing wave modes = h f Planck’s Radiation Law 2 c h 2 5 1 e hc / kT 1 h = 6.626e-34 Js 3.6 Photoelectric Effect http://en.wikipedia.org/wiki/Heinrich_Hertz http://en.wikipedia.org/wiki/Induction_coil Heinrich Hertz Verified Maxwell equations prediction of electromagnetic waves ~1887 3.6 Photoelectric Effect Photoelectric Effect Investigations ~1900 1. Higher intensity light did not change the point at which current started to flow. (i.e. energy of the electrons) 1’. More total incident energy did not increase the energy of individual electrons. 2. Different colors of light changed the starting point for current flow. 3.6 Photoelectric Effect eVo hf typically a few Volts at most Implications: 1. EM waves have fixed energies (EM field is quantized) 2. Electrons are bound in a material by an amount determined by the composition 3.7 X-Ray Production (Bremsstralung + Characteristic X-Rays) At fixed HV 35kV Roentgen characteristic lines min max Energy E photon hf f c E photon hc 3.7 X-Ray Production (Bremsstralung + Characteristic X-Rays) Roentgen 3.7 X-Ray Production (Bremsstralung + Characteristic X-Rays) Do TV Sets Give Off X-Rays? http://en.wikipedia.org/wiki/Cathode_ray_tube X-rays may be produced when electrons, accelerated by high voltage, strike an obstacle while traveling in a vacuum, as in a TV containing a cathode ray tube (CRT). Since many of the components in television sets operate at thousands of volts, there is the potential for x-ray generation. These components may produce xrays capable of escaping from the television receiver or CRT. This unintentional emission of xradiation can pose a potential hazard and must be controlled. http://www.fda.gov/Radiation-EmittingProducts/ResourcesforYouRadiationEmittingProducts/ucm252764.htm http://www.orau.org/ptp/collection/xraytubescoolidge/xraytubescoolidge.htm http://www.tradevv.com/chinasuppliers/eiffelgu_p_23e13/china-Portable-X-ray-flaw-detector-ceramic-tube.html http://www.aerospacendt.com/Radiography.htm Computed tomography (CT) scanning, also called computerized axial tomography (CAT) scanning, is a medical imaging procedure that uses x-rays to show cross-sectional images of the body. A CT imaging system produces cross-sectional images or "slices" of areas of the body, like the slices in a loaf of bread. These cross-sectional images are used for a variety of diagnostic and therapeutic purposes. How a CT system works: http://www.strokecenter.org/patients/diagnosis/ct.htm http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115317.htm http://medicaltools.onsugar.com/Ct-Scan-Abdomen-Cancer-15819123 http://www.strokecenter.org/patients/diagnosis/ct.htm http://info.shields.com/bid/43193/MRI-Images-torn-ACL-and-normal-ACL Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an Xray source and fluorescent screen between which a patient is placed. However, modern fluoroscopes couple the screen to an X-ray image intensifier and CCD video camera allowing the images to be recorded and played on a monitor. http://en.wikipedia.org/wiki/Fluoroscopy 3.8 Compton Effect Thomson Scattering In classical description, scattering occurs via dipole and scattered photon of same frequency (wavelength) 3.8 Compton Scattering h 1 cos mc ' h/mc =2.2426e-12 m 3.9 Pair Production & Positron Annihilation Pair Production only if hf 2mec2 2(0.511) 1.022 MeV 3.9 Pair Production & Positron Annihilation Positron Annihilation Photons come out back-to-back Photon energies are 0.511 MeV each Positron emission tomography (PET) is a nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule. Threedimensional images of tracer concentration within the body are then constructed by computer analysis. If the biologically active molecule chosen for PET is FDG, an analogue of glucose, the concentrations of tracer imaged then give tissue metabolic activity, in terms of regional glucose uptake. http://en.wikipedia.org/wiki/PET_scanner http://archives.drugabuse.gov/newsroom/03/NR9-08.html Summary of Chapter 03 Strange things not known from classical physics • New things – Cathode rays electrons – X-rays • Line spectra – Gaseous discharges show lines rather than continous spectrum • Blackbody radiation – Rayleigh-Jeans classical formula clearly incorrect at explaining spectrum – Planck: oscillators with fixed energies • Compton scattering – Scattered photons have different wavelength in contast to classical description • Pair production & Positron annihilation – Waves change into particles and vice versa